When a driver is probed through __driver_attach(), the bus' match() callback is called without the device lock held, thus accessing the driver_override field without a lock, which can cause a UAF.
Fix this by using the driver-core driver_override infrastructure taking care of proper locking internally. Note that calling match() from __driver_attach() without the device lock held is intentional. [1] Link: https://lore.kernel.org/driver-core/[email protected]/ [1] Reported-by: Gui-Dong Han <[email protected]> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220789 Fixes: e95060478244 ("rpmsg: Introduce a driver override mechanism") Signed-off-by: Danilo Krummrich <[email protected]> --- drivers/rpmsg/qcom_glink_native.c | 2 -- drivers/rpmsg/rpmsg_core.c | 43 +++++-------------------------- drivers/rpmsg/virtio_rpmsg_bus.c | 1 - include/linux/rpmsg.h | 4 --- 4 files changed, 7 insertions(+), 43 deletions(-) diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c index 9ef17c2e45b0..e9d1b2082477 100644 --- a/drivers/rpmsg/qcom_glink_native.c +++ b/drivers/rpmsg/qcom_glink_native.c @@ -1623,7 +1623,6 @@ static void qcom_glink_rpdev_release(struct device *dev) { struct rpmsg_device *rpdev = to_rpmsg_device(dev); - kfree(rpdev->driver_override); kfree(rpdev); } @@ -1859,7 +1858,6 @@ static void qcom_glink_device_release(struct device *dev) /* Release qcom_glink_alloc_channel() reference */ kref_put(&channel->refcount, qcom_glink_channel_release); - kfree(rpdev->driver_override); kfree(rpdev); } diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c index 96964745065b..2b9f6d5a9a4f 100644 --- a/drivers/rpmsg/rpmsg_core.c +++ b/drivers/rpmsg/rpmsg_core.c @@ -358,33 +358,6 @@ rpmsg_show_attr(src, src, "0x%x\n"); rpmsg_show_attr(dst, dst, "0x%x\n"); rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n"); -static ssize_t driver_override_store(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) -{ - struct rpmsg_device *rpdev = to_rpmsg_device(dev); - int ret; - - ret = driver_set_override(dev, &rpdev->driver_override, buf, count); - if (ret) - return ret; - - return count; -} - -static ssize_t driver_override_show(struct device *dev, - struct device_attribute *attr, char *buf) -{ - struct rpmsg_device *rpdev = to_rpmsg_device(dev); - ssize_t len; - - device_lock(dev); - len = sysfs_emit(buf, "%s\n", rpdev->driver_override); - device_unlock(dev); - return len; -} -static DEVICE_ATTR_RW(driver_override); - static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -405,7 +378,6 @@ static struct attribute *rpmsg_dev_attrs[] = { &dev_attr_dst.attr, &dev_attr_src.attr, &dev_attr_announce.attr, - &dev_attr_driver_override.attr, NULL, }; ATTRIBUTE_GROUPS(rpmsg_dev); @@ -424,9 +396,11 @@ static int rpmsg_dev_match(struct device *dev, const struct device_driver *drv) const struct rpmsg_driver *rpdrv = to_rpmsg_driver(drv); const struct rpmsg_device_id *ids = rpdrv->id_table; unsigned int i; + int ret; - if (rpdev->driver_override) - return !strcmp(rpdev->driver_override, drv->name); + ret = device_match_driver_override(dev, drv); + if (ret >= 0) + return ret; if (ids) for (i = 0; ids[i].name[0]; i++) @@ -535,6 +509,7 @@ static const struct bus_type rpmsg_bus = { .name = "rpmsg", .match = rpmsg_dev_match, .dev_groups = rpmsg_dev_groups, + .driver_override = true, .uevent = rpmsg_uevent, .probe = rpmsg_dev_probe, .remove = rpmsg_dev_remove, @@ -560,11 +535,9 @@ int rpmsg_register_device_override(struct rpmsg_device *rpdev, device_initialize(dev); if (driver_override) { - ret = driver_set_override(dev, &rpdev->driver_override, - driver_override, - strlen(driver_override)); + ret = device_set_driver_override(dev, driver_override); if (ret) { - dev_err(dev, "device_set_override failed: %d\n", ret); + dev_err(dev, "device_set_driver_override() failed: %d\n", ret); put_device(dev); return ret; } @@ -573,8 +546,6 @@ int rpmsg_register_device_override(struct rpmsg_device *rpdev, ret = device_add(dev); if (ret) { dev_err(dev, "device_add failed: %d\n", ret); - kfree(rpdev->driver_override); - rpdev->driver_override = NULL; put_device(dev); } diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c index 8d9e2b4dc7c1..e0dacb736ef9 100644 --- a/drivers/rpmsg/virtio_rpmsg_bus.c +++ b/drivers/rpmsg/virtio_rpmsg_bus.c @@ -373,7 +373,6 @@ static void virtio_rpmsg_release_device(struct device *dev) struct rpmsg_device *rpdev = to_rpmsg_device(dev); struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); - kfree(rpdev->driver_override); kfree(vch); } diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h index fb7ab9165645..c2e3ef8480d5 100644 --- a/include/linux/rpmsg.h +++ b/include/linux/rpmsg.h @@ -41,9 +41,6 @@ struct rpmsg_channel_info { * rpmsg_device - device that belong to the rpmsg bus * @dev: the device struct * @id: device id (used to match between rpmsg drivers and devices) - * @driver_override: driver name to force a match; do not set directly, - * because core frees it; use driver_set_override() to - * set or clear it. * @src: local address * @dst: destination address * @ept: the rpmsg endpoint of this channel @@ -53,7 +50,6 @@ struct rpmsg_channel_info { struct rpmsg_device { struct device dev; struct rpmsg_device_id id; - const char *driver_override; u32 src; u32 dst; struct rpmsg_endpoint *ept; -- 2.53.0
